Searching for evidence of inflation in the Cosmic Microwave Background
Shortly after the birth of the Universe, space was filled with a glowing red-hot plasma. As the universe expanded and cooled over the next 13.8 billion years, the glow of that plasma redshifted to longer wavelengths and is observed today by our telescopes as the Cosmic Microwave Background (CMB). Spatial variations of CMB intensity provide a record of conditions in the early universe and anchor our understanding of modern cosmology. Variations of CMB polarization might contain direct evidence of early accelerated expansion or cosmic inflation, potentially elucidating how the universe began. Searching for inflation in CMB polarization requires exquisite camera sensitivity, control of instrument systematics, disentangling CMB from galactic foregrounds and removing gravitational-lensing-induced distortion in the CMB field. Over the past decade, experiments such as the BICEP/Keck program of CMB telescopes at the South Pole have been making deep images of the polarized microwave sky to search for inflation. In this talk, I will provide an overview of the BICEP/Keck instrumentation and its latest science results, as well as prospects for detection in the near future.